如何在C中比较两个指针变量？

#include <stdio.h>

int main() {
    int num1 = 10;
    int num2 = 20;
    
    int* ptr1 = &num1;
    int* ptr2 = &num2;
    int* ptr3 = &num1;
    
    // 直接比较指针变量的值
    if (ptr1 == ptr2) {
        printf("ptr1 and ptr2 are equal\n");
    } else {
        printf("ptr1 and ptr2 are not equal\n");
    }
    
    if (ptr1 == ptr3) {
        printf("ptr1 and ptr3 are equal\n");
    } else {
        printf("ptr1 and ptr3 are not equal\n");
    }
    
    // 比较地址值
    if (&ptr1 == &ptr2) {
        printf("Address of ptr1 and ptr2 are equal\n");
    } else {
        printf("Address of ptr1 and ptr2 are not equal\n");
    }
    
    // 比较指向的值
    if (*ptr1 == *ptr2) {
        printf("Value pointed by ptr1 and ptr2 are equal\n");
    } else {
        printf("Value pointed by ptr1 and ptr2 are not equal\n");
    }
    
    return 0;
}

ptr1 and ptr2 are not equal
ptr1 and ptr3 are equal
Address of ptr1 and ptr2 are not equal
Value pointed by ptr1 and ptr2 are not equal